1. Field of Invention
This invention relates generally to the field of surgery, and more particularly to an apparatus for detection of a probe penetration into a body cavity.
2. Description of Related Art
Prior techniques for surgery requiring insertion of a needle or a small diameter probe into and through the tissue layers of a patient include laparoscopic surgery with a laparoscope inserted into the interior of the abdominal cavity. Another surgical technique includes insertion of a verres needle through tissue layers and into the abdominal cavity at about the umbilical region as a part of an insufflation technique, which is the act of blowing a vapor, gas, and/or air into a body cavity such as the abdominal cavity for sufficient distension of the cavity to allow for examination and manipulation of the cavity contents. Insertion techniques for injections of medications include insertion of needle and/or a cannula/catheter through the skin and into blood vessels or other body cavities for injection of fluids. Each of the above insertion techniques require the practitioner to be able to judge by the feel of the insertion of the needle as to whether the needle end finds the target vein, layer of tissue, or body cavity. For example, during investigations of the abdominal cavity, a practitioner must determine the progress of insertion of the penetrating needle end through the tissue layers of the umbilical region of the abdominal cavity.
The prior techniques utilized by practitioners include detection of sound as the needle end penetrates, and/or the utilization of touch and feel of the physical resistance, or lack of resistance, against the needle end during penetration. An additional prior technique includes measuring changes in pressure maintained at the penetrating end of a verres needle during penetration of the multiple layers of the umbilical region of the abdomen. The multiple layers of the umbilical region include the outer skin layer, a fat cell layer of variable thickness, a fascia layer of variable tissue thickness and abdominal muscles, a peritoneum layer, and the abdominal cavity. Each of the layers of the umbilical region may vary in depth between patients, and there may be the presence of scar tissue, therefore the penetration of a needle or a similar probe during the insufflation technique requires an extremely delicate sequence of steps.
It is beneficial to medical practitioners to have a reliably reproducible monitoring system having feedback notification that indicates to an operator when each tissue layer is penetrated and when a body cavity is penetrated by an insertion end of a needle or probe. Further, it is beneficial to have a method for operation of a system utilized for monitoring the stages of penetration of an insertion end of a needle or probe through each one of a plurality of outer layers covering a body cavity of a patient.
Other subjects and advantages will be accomplished by the present invention which includes a probe penetration detector system and a method of operation of the probe penetration detector system during surgical procedures. The detector system includes an electrically conductive probe, cannula, or needle which also serves as an antenna adapted for being inserted a selected depth into the body tissue and body cavity of the patient, and a transmitter for generation of a plurality of radio frequency signals transmitted to the antenna. The system further includes an electrical connection between the antenna and the transmitter, and a detector to monitor a selected feedback parameter for the antenna, with the detector providing notification of the selected feedback parameter to the operator corresponding to the proximate location of the probe, cannula, or needle. Notification of the selected feedback parameter to the operator provides an indicator of the depth of insertion of the probe, cannula, or needle antenna into the body tissue and body cavity of the patient.
More specifically, an embodiment of the electrically conductive probe includes a probe penetration unit, such as a cannula or needle, having a probe connected to a transmitter providing a plurality of signals of a selected frequency to the probe as the probe is inserted through each one of a plurality of tissue layers covering a body cavity. The detector includes analyzer circuitry and software to aid in determining when the probe has reached a location in the body at which the signal reflected from the probe approaches a characteristic value.
For example, the analyzer circuitry can calculate a standing wave ratio of the radio frequency signals transmitted to the probe compared to the, feedback parameter signals reflected from the probe. Circuitry coupled with audio and/or visual notification equipment is provided to notify the operator of the feedback parameter signals as the probe is inserted through each one of a plurality of the tissue layers, and to notify the operator that the probe is inserted into the appropriate body cavity of a patient.